Tong assembly for drill pipes

ABSTRACT

A tong apparatus for use with a rotary drill apparatus whereby threadedly engaged sections of drill pipe may be disconnected. The apparatus comprises: a mounting element for positioning around a section of drill pipe and spaced therefrom, a coaxial extension above said mounting element having means for connecting the apparatus to the power swivel of the rotary drill apparatus, at least one pivotal member on the mounting element rotatable about a pivot axis and having a pipe gripping portion for contacting the section of drill pipe when the pivot member rotates in one direction with respect to the mounting element and which moves away from the section of drill pipe when the pivotal member rotates in the other direction with respect to the mounting element. An inertial element is integral with the mounting element and is capable of movement with respect to the pivot axis and capable of urging the pivotal member to move tangentially about the pivot axis.

United States Patent Primary Examiner-Andrew R. Juhasz AssistantExaminer-James F. Coan Attorney-William George Hopley ABSTRACT: A tongapparatus for use with a rotary drill apparatus whereby threadedlyengaged sections of drill pipe may be disconnected. The apparatuscomprises: a mounting element for positioning around a section of drillpipe and spaced therefrom, a coaxial extension above said mountingelement having means for connecting the apparatus to the power swivel ofthe rotary' drill apparatus, at least one pivotal member on the mountingelement rotatable about a pivot axis and having a pipe gripping portionfor contacting the section of drill pipe when the pivot member rotatesin one direction with respect to the mounting element and which movesaway from the section of drill pipe when the pivotal member rotates inthe other direction with respect to the mounting element. An inertialelement is integral with the mounting element and is capable of movementwith respect to the pivot axis and capable of urging the pivotal memberto move tangentially about the pivot axis.

TONG ASSEMBLY FOR DRILL PIPES This invention relates generally to therotary piercing of earth formations by means of a drill pipe, the upperend of which is rotated by a power swivel and the lower end of whichcarries a bit adapted to bite through the particular earth formationbeing pierced. More particularly, this invention relates to a tongapparatus for use as an accessory with rotary earthpiercing drills, andcapable of gripping the drill pipe from the outside and rotating thesame, even though the drill pipe itself be loosely threaded, or notthreaded at all, into the power swivel.

In the rotary earth-piercing art, it is generally desirable to mechanizeas much of the process as possible, in order to reduce the amount ofmanual labor required for a particular job, and thereby increase boththe efficiency and speed of a particular operation.

The portion of a drilling operation to which this invention isparticularly related is that which involves the disassembly of thesegmented drill pipe after the drilling of a particular bore hole hasbeen completed. Generally speaking, the sequence of events involved indisassembling a segmented drill pipe is obvious. The power swivel, whichis usually hydraulically operated and is capable of vertical motionalong an appropriate guideway, will have arrived, upon completion of thedrilling, at a given point along its vertical path of movement. Assumingthat this point is at or near the lower end of its path of movement, thedrill pipe disassembly operation is carried out by raising the powerswivel to a point at or near the top of its vertical movement path,carrying with it the entire length of drill pipe, whereupon theuppermost segment of drill pipe is unscrewed from both the power swiveland the segment next beneath the uppermost segment. Some sort of visearrangement is required to grip the second segment in the line while theuppermost segment is being removed. Following this, the power swiveldescends and engages the second segment (now the uppermost) and againlifts the entire length of the segmented drill pipe upwardly until itreaches the top of its travel. At this point, the third segment isgripped in the vise, and the second segment is unscrewed from the powerswivel and from the third segment. This process is repeated until theentire length of the segmented drill pipe is disassembled.

The object of this invention is to provide an accessory for the powerswivel mechanism which permits the tight threaded engagement of adjacentsegments of drill pipe to be broken automatically, obviating thenecessity of breaking the engagement manually.

Accordingly, this invention provides a tong assembly for selectivelygripping and releasing a drill pipe, comprising: a mounting element forpositioning adjacent a drill pipe without contacting the drill pipe, atleast one pivotal member mounted on the mounting element to rotate abouta pivot axis, the pivotal member having spaced from said pivot axis apipegripping portion which moves toward and into contact with the drillpipe when the pivotal member rotates in one direction with respect tosaid mounting element and which moves away from the drill pipe when thepivotal member rotates in the other direction with respect to saidmounting element, and an inertial element capable of movement withrespect to said pivot axis and adapted, upon such movement, to urge apart of the pivotal member to move tangentially about said pivot axis.

One embodiment of this invention is shown in the accompanying drawings,in which like numerals denote like parts throughout the several views,and in which:

FIG. 1 is a schematic elevational view of nine sequential steps in theremoval of a segment of drill pipe;

FIG. 2 is an elevational view of the tong assembly of this invention;

FIG. 3 is a view of the tong assembly of FIG. 2 looking from right toleft at the end of the tong assembly;

FIG. 4 is a cross-sectional view of the tong assembly of FIG. 2 taken atthe line 44 in FIG. 2; and

FIG. 5 is a partial sectional view similar to that of FIG. 4, showingone of the elements in FIG. 4 in a different position.

Turning first to FIG. 1, the general sequence of operations in theremoval of one segment of a segmented drillpipe will be described. InFIG. 1, the sequential positions are denoted by the letters A-J, andtake place in alphabetical order. In FIG. 1A the column 10 denotes theguideway or track along'which a power swivel 12 is vertically movable.The line 14 is a segmented drill pipe and the portion visible in FIG. 1Ais the uppermost segment of the drill pipe. The uppermost segment of thedrill pipe 14 extends downwardly into a drill hole 16 which is in theprocess of being drilled in FIG. 1A. The crossline 17 on the drill stem14 denotes the point at which the drill stem 14 is threaded onto arotary shaft 18 extending downwardly from the power swivel 12. A vise 20is mounted on the column 10 and is represented by an anvil and a point,both schematically drawn. The tong assembly of this invention is shownat 22 and includes a vertical extension 23. The vertical extension 23 issecurely threaded to an annular shaft 24 which extends downwardly fromthe power swivel 12 and is adapted to rotate with the shaft 18. Thecrossline at 25 denote the point at which the vertical extension 23 ofthe tong assembly 22 is threaded to the annular shaft 24.

The tong assembly 22 contains a pipe-gripping means which has beenrepresented by two opposing arrows in FIG. 1. During the drillingoperation shown in FIG. 1A, the arrows inside the tong assembly 22 areshown spaced away from the drill pipe 14, because the latter is entirelyfree of contact with the tong assembly 22 at this point. In FIG. 1Aabove the power swivel 12, the letter R is surrounded by a rotationalarrow which indicates the direction of rotation of the tong assembly 22as seen from above looking downwardly. Thus, in FIG. 1A, the drillingoperation involves a continuous clockwise rotation of the shaft 18, thedrill pipe 14 and, although of no importance at this point, the tongassembly 22.

It is now assumed that the drilling operation has been completed, andthat the power swivel 12 has ceased to rotate the drill pipe 14. In FIG.1B, rotation of the drill pipe 14 has stopped, and the vise 20 has beenmade to firmly grip the uppermost segment of the drill pipe 14. In FIG.1C, the power swivel 12 is caused to rotate a fraction of a turn in thecounterclockwise direction, and this breaks the tight threadedconnection between the upper segment of the drill pipe 14 and the shaft18 extending from the power swivel 12. The broken but still looselyengaged threaded connection between the upper segment of the drill pipeand the shaft 18 is represented in FIG. 1C by two horizontal crosslineslinked together by brackets. This means that, although it is possible torotate the shaft 18 with respect to the upper segment of the drill pipe14, the threads of these two elements are still sufficiently engagedthat the upper segment cannot be pulled vertically away from the shaft18. Above the power swivel 12 in FIG. 1C, the rotational diagram denotesa fraction of one revolution beginning at the start S and being arrestedat A.

In FIG. 1D, the power swivel 1215 not rotating, and the vise 20 has beenwithdrawn from engagement with the drill pipe 14. Throughout theremainder of FIG. 1 to be discussed, the numerals will be reduced to aminimum in order to avoid confusion.

In FIG. IE, the power swivel 12 has been raised to a point at or nearthe upper end of its travel, and has drawn with it the entire length ofthe drill pipe 14, including all of its segments, due to the fact thatthe threaded engagement between the upper segment of the drill pipe 14and the shaft 18, although no longer a tight connection, is sufficientto bear the weight of the drill pipe 14. The power swivel 12 is thusraised to a position in which the threaded connection between theuppermost segment of drill pipe and the next lower segment is positionedabove the vise 20.

As seen in FIG. IF, the vise 20 is next brought into engagement with thesecond segment, while the remainder of the ap paratus remainsstationary.

In FIG. 1G a high-speed fractional rotation of the tong assembly 22 inthe counterclockwise direction succeeds, by a mechanism later to beexplained, in bringing the pipe-gripping elements within the tongassembly 22 into tight engagement with the uppermost segment of thedrill pipe. In the rotational diagram above the power swivel 12 in FIG.16, the fractional rotation begins at S and ends at A.

In FIG. 1H, now that the pipe-gripping means in the tong assembly is inengagement with the upper segment of the drill pipe, furthercounterclockwise rotation of the tong assembly 22 turns the uppersegment of the drill stem, and causes the latter to be rotated withrespect to the second segment. Because the vise 20 is restraining thesecond segment from rotation, the threaded connection between the twosegments is broken. It is desirable at this stage to completely unscrewthe upper segment from the segment beneath.

In FIG. 1.], another high-speed fractional rotation of the tong assembly22, this time in the clockwise direction, succeeds in disengaging thepipe-gripping means within the tong assembly from the upper segment ofthe drill pipe 14. When the stage shown in FIG. H has been reached, theupper segment can be held manually while the power swivel I2 completelyunscrews the shaft 18.

Turning now to FIG. 2, the tong assembly 22 is shown on its side: alower cylindrical compartment 27 has a concentric cylindrical shaft 28extending rightwardly (upwardly when in use) from the compartment 27.The shaft 28 is preferably of integral manufacture, and is seen to beprovided with exterior threads 30 at its upper end, and a partly knurledexpanded midportion 32. The cylindrical compartment 27 is definedgenerally between a first annular wall 34 which is fixed rigidly to theshaft 28, and a second annular wall 35 which is fixed rigidly to thefirst annular wall 34 by means of three internal pillars 38 which areshown in cross section in FIG. 4, and which extend perpendicularlybetween the two walls 34 and 35.

Attention is now directed to FIG. 4, which is a cross-sectional viewshowing the internal components of the compartment 27. Extending betweenthe two walls 34 and 35 are three pivot pins 40, spaced at 120intervals, and located approximately centrally between the outerperiphery 41 and the inner periphery 42 of the annular walls 34 and 35.The inner periphery 42 of the walls 34 and 35 coincides with the innercircumference of the shaft 28 where it joins the annular wall 34.

Three pivotal members 44 are mounted to rotate about the pivot axesdefined by the center lines of the pivot pins 40. The shape, size andoperation of all three pivotal members are identical, and for thisreason attention will be directed to the upper right-hand pivotal member44 in FIG. 4 throughout the remainder of this description. The pivotalmember 44 has been shown to be circular in cross section, and althoughit is convenient to provide the members 44 in the shape of discs, itwill be appreciated that this shape is by no means essential to theinvention. The pivotal member 44 supports a pipegripping jaw 46 at alocation spaced from the pivot axis defined by the center line of thepivot pin 40. As can be seen in FIG. 4, the particular location of thejaw 46 with respect to the pivot pin 40 is such that the jaw 46 movestoward the drill pipe 14 when the pivotal member 44 rotates in thecounterclockwise direction with respect to the annular wall 35, andmoves away from the drill pipe 14 when the pivotal member 44 rotates inthe clockwise direction with respect to the annular wall 35.

Mounted for loose and independent movement with respect to the two walls34 and 35 is a cylindrical inertial element 48 the exterior surface ofwhich is visible in FIG. 2, and a cross: sectional view of which isvisible in FIG. 4. The inertial element 48 is provided with threetangentially elongated slots 50 at three locations spaced 120 from eachother, and each pivotal member 44 has an outwardly extending pin 52which passes through one of the slots 50 and has on its far end a head53 the dimensions of which make it too large to pass through the slot50. The mechanical interference between the head 53 and the slot isclearly seen in FIG. 2.

The element 48 is very heavy, and its inertia is utilized to move thepins 52 in one direction or another, thereby rotating the jaws 46 eitherinto engagement or out of engagement with the drill pipe 14.

The operation of the tong assembly at the stage shown in FIG. 1G,wherein the jaws 46 are caused to swing inwardly and tightly grip thedrill pipe 14, will now be described with particular reference to FIGS.4 and 5. In FIG. 5, only one pivotal member of the tong assembly hasbeen shown. FIG. 5 shows the position of the pivotal member 44 duringall of the stages represented by FIGS. 1A through 1F. It is observedthat the jaw 46 is withdrawn from engagement with the drill pipe 14. Thehigh-speed fractional rotation of the power swivel 12 shown above FIG.10 causes the wall 35 abruptly to move in the direction of the arrow Tin FIG. 5. Naturally, the pivot pin 40 also undergoes this rapidmovement. The drill pipe I4, however, which is at this point onlyloosely threaded to the shaft 18, does not rotate. Also, the element 48,because of its high inertia, does not rotate initially with the wall 35unless it is already in the position shown in FIG. 5, wherein the upperleft edge of the slot 50 is in contact with the pin 52, and the lattercannot move any further to the right (clockwise direction about thepivot pin 40) because the head 53 is binding against the longitudinaledges of the slot 50. If the element 48 is not in the FIG. 5 position,it remains stationary until the FIG. 5 configuration is reached, atwhich time a strong counterclockwise impetus is transmitted to theelement 48, to start it rotating in the counterclockwise direction atthe same speed as the wall 35. The tong assembly, and thus the wall 35,is then suddenly and abruptly stopped, which means that the pivot pin 40is also abruptly stopped. The inertial element 48, however, continues torotate in the counterclockwise direction, as shown by the arrows P inFIG. 4, and this continuing rotation brings the other edges of the slots50 into smart contact with the pins 52, causing the pivotal members 44to rotate in the counterclockwise direction at high speeds, driving thejaws 46 against the outer surface of the drill pipe 14. Once the jaws 46have been thus locked against the surface of the drill pipe 14, thepower swivel 12 can be further rotated in the counterclockwisedirection, this time at slower speed, until the desired degree ofunscrewing has been achieved (see FIG. 1H). As mentioned above, it isdesirable to continue this slow-speed counterclockwise rotation untilthe threaded engagement between the uppermost pipe segment and the nextlower pipe segment has been completely unscrewed. After the jointbetween the first and second pipe segments has been completelyunscrewed, the jaws 46 can be disengaged from the outer surface of thedrill pipe 14 by utilizing the inertia of the inertial element 48 in thesame manner as before, but in the opposite direction. That is, the tongassembly is given a fraction of a turn in the clockwise direction atvery high speed (carrying with it the upper segment of the drill pipe14), and giving a clockwise impetus to the inertial element 48. When theclockwise rotation of the tong assembly is abruptly stopped, theinertial element 48 continues its clockwise rotation, coming into smartcontact with the pins 52, and causing the pivotal members 44 to rotatein the clockwise direction and break the jaws 46 loose from the surfaceof the drill pipe 14. This latter sequence has not been illustrated indetail, as it will be obvious in view of the description of theengagement of the jaws 46 with the drill pipe 14, taking place in FIG.1G.

It is desirable to provide an overtoggling biasing means which tends tomaintain the heads 53 in either limit position, and such a means hasbeen shown in FIGS. 2 and 3. Affixed to each head 53 is an extensionwhich projects beyond the wall 34 and carries a pivoting member 56 towhich one end of a helical compression spring 58 is attached. The otherend of each compression spring 58 is attached to a projection 60 whichis fixed to the wall 34. The attachment between the projection 60 andthe spring 58 is such as to permit the compression spring 58 to swingthrough a limited are as the head 53 moves back and forth between itstwo limit positions shown in solid and dotted lines in H6. 3. Eachprojection 60 is situated generally between its respective head 53 and apoint 62 which defines the axis about which rotates the pivot member 44carrying that head 53. By locating the projection 60 approximatelyequidistant from the head 53 in its two limit positions, an overtogglinglight-switch type of action is assured, in which the compression spring58 is at its greatest length when the head 53 is in either limitposition, and is at its minimum length when the head 53 is midwaybetween its two limit positions.

It is pointed out that, although three pivotal members 44 have beenprovided in the embodiment illustrated in the drawings, the inventionwould be worked so long as there were at least one of such pivotalmembers provided with a jaw capable of engaging the surface of the drillpipe 14.

it will further be obvious that, although one particular form of theinertial element 48 has been shown, a number of other designs could beelaborated wherein a different construction, particularly for theinertial element 48, were employed. For

example a separate inertial element could be provided for each of thepivotal members 44. Again, the inertial element 48, instead of beingmounted exteriorly of the pivotal members 44, could be mounted inside ofthe pivotal members 44. Such a design would likely mean that engagementof the jaws 46 with the drill pipe 14 would entail rapid fractionalrotation of the tong assembly in the opposite direction from that shownand described above.

While one embodiment of this invention has been shown and describedherein, those skilled in the art will appreciate that changes andmodifications may be made therein without departing from the spirit andscope of this invention as defined in the appended claims.

1. A tong assembly for selectively gripping and releasing a drill pipe,comprising:

an annular mounting element for positioning adjacent a drill pipe andhaving a central aperture capable of receiving a drill pipe withoutcontact, said element having a coaxial shaft extension at one endadapted to be threadedly secured to a power swivel of a drillingapparatus,

three pivotal members on the side of said annular mounting elementremote from said coaxial shaft extension, said members spaced axially atapproximately in the annular mounting element and each pivotal memberadapted to rotate about a pivot axis in a plane normal to the axis ofsaid drill pipe, each pivotal member having a pipe-gripping portionspaced from its pivot axis and moveable toward and in contact with saiddrill pipe when said pivot member rotates in one direction with respectto said annular mounting element and moves away from said drill pipewhen the pivotal member rotates in the other direction with respect tosaid annular mounting element,

an annular inertial element loosely retained in said annular mountingelement and capable of movement with respect to each of said pivotalmembers,

a part of each of said pivotal members projecting generally away fromthe pipe gripping portion through an opening in said inertial elementwhereby a sudden change in the rotational velocity of the annularmounting element results in a relative rotational movement between theannular mounting element and the inertial element thereby urging saidpart of each of said pivotal members to move tangentially about thepivot axis of the respective pivotal member.

2. A tong assembly as claimed in claim 1 which includes overtogglingbearing means adapted to urge said projecting part of at least one ofsaid pivotal members in either one direction to maintain thepipe-gripping portion in pipegripping position or in the oppositedirection to maintain the pipe-gripping portion away from pipe-grippingposition.

3. A tong assembly as claimed in claim 2 wherein said annular mountingelement has a first annular wall and a second annular wall rigidlysecured to said first wall, said annular inertial element looselyretained between said first and said second wall.

1. A tong assembly for selectively gripping and releasing a drill pipe,comprising: an annular mounting element for positioning adjacent a drillpipe and having a central aperture capable of receiving a drill pipewithout contact, said element having a coaxial shaft extension at oneend adapted to be threadedly secured to a power swivel of a drillingapparatus, three pivotal members on the side of said annular mountingelement remote from said coaxial shaft extension, said members spacedaxially at approximately 120* in the annular mounting element and eachpivotal member adapted to rotate about a pivot axis in a plane normal tothe axis of said drill pipe, each pivotal member having a pipe-grippingportion spaced from its pivot axis and moveable toward and in contactwith said drill pipe when said pivot member rotates in one directionwith respect to said annular mounting element and moves away from saiddrill pipe when the pivotal member rotates in the other direction withrespect to said annular mounting element, an annular inertial elementloosely retained in said annular mounting element and capable ofmovement with respect to each of said pivotal members, a part of each ofsaid pivotal members projecting generally away from the pipe grippingportion through an opening in said inertial element whereby a suddenchange in the rotational velocity of the annular mounting elementresults in a relative rotational movement between the annular mountingelement and the inertial element thereby urging said part of each ofsaid pivotal members to move tangentially about the pivot axis of therespective pivotal member.
 2. A tong assembly as claimed in claim 1which includes overtoggling bearing means adapted to urge saidprojecting part of at least one of said pivotal members in either onedirection to maintain the pipe-gripping portion in pipe-grippingposition or in the opposite direction to maintain the pipe-grippingportion away from pipe-gripping position.
 3. A tong assembly as claimedin claim 2 wherein said annular mounting element has a first annularwall and a second annular wall rigidly secured to said first wall, saidannular inertial element loosely retained between said first and saidsecond wall.